1.0 Field of the Invention
The present invention concerns the coordinated programming and test control of multiple independent, but irrigation-function interrelated, programmable electronic irrigation controllers within an irrigation system.
2.0 Background of the Invention
Large irrigation systems, such as those for golf courses and parks, typically use many dozens of independently operative irrigation controllers. Each irrigation controller controls a number of valves that gate the flow of irrigation water, typically to eight valves per controller. Because each irrigation controller must be electrically wired to all valves that it controls, it is infeasible to have the many hundreds or thousands of valves in a large area irrigation system controlled by a single controller.
Although each irrigation controller is independent in its operation, the irrigation control exercised by multiple irrigation controllers is typically interrelated, and must be coordinated. This is because the piping of irrigation water to the stations, or valves, of a number of irrigation controllers is usually in series, one station to the next. A fundamental rule of irrigation control is that only such numbers of irrigation stations should be simultaneously enabled for irrigation watering as do not, resultant to the drop on hydrostatic pressure and flow caused by each "on" station, adversely affect irrigation watering pressures, flows, and patterns at any one(s) of the simultaneously enabled stations. Because most irrigation piping is of minimal diameter and cost consonant with the water flow and pressure requirements of a single irrigation station, application of the rule normally requires that only one irrigation station should be enabled any one time.
Enabling one only irrigation station, or valve, to be on at one time among all the valves controlled by a single irrigation controller is merely a matter of the setup, or programming, of that one irrigation controller. However, if separate and independent irrigation controllers must be coordinated, as is typically required due to the plumbing of irrigation water, then matters become more difficult. A programmer/user of interrelated irrigation controllers must understand the hydrodynamic relationships of the valves controlled by each. These relationships may be several and may be at several hydrodynamic levels within a large irrigation system. In accordance with this understanding, the programmer/user must program irrigation at each irrigation controller in consideration of his/her programming of the other irrigation controllers.
Even when the necessary coordination of irrigation control programming is kept track of on paper, its actual implementation is difficult and fraught with error. The irrigation controllers themselves are typically difficult and time consuming to program. They are required to be programmed where located, meaning in the field. The weather conditions under which the irrigation controllers must be programmed, and the caliber and diligence of the workers that must tend to the programming, are not always good. Considerable difficulty of coordination between irrigation controllers is experienced. It is hard to affect any appreciable change at any one controller until all controllers are reasonably well coordinated.
These difficulties tend to impart a great deal of undesired rigidity to the entire irrigation programming process. The system wide reprogramming of an irrigation system because of variations in rainfall, seasonal variations, changed site requirements and numerous other reasons is often undesirably foregone simply because it is excessively difficult to plan, setup, or repeatedly setup coordinated irrigation control.
One previous approach in dealing with the difficulties in the coordinated setup, or programming, of multiple independent but functionally interrelated irrigation controllers within a single irrigation system has been based on the establishment of one master and several satellite irrigation controllers. The master irrigation controller communicates with its satellite irrigation controllers to sequence their respective operations. Flexibility in scheduling is typically constrained by the nature of the sequential control of the satellite irrigation controllers. The expense of a wired communication network is incurred. The problem of coordinating multiple interrelated irrigation controllers is simply moved to a higher level because multiple master irrigation controllers may themselves now require coordinated set-up, now at typically increased complexity, one to another.